Field of the Invention
The present invention relates to an integrated module multi-chamber vacuum processing system provided with a substrate transferring robot assembly for transferring a substrate between a load-lock chamber and processing chamber or between processing chambers.
Background Art
For a substrate multi-step vacuum processing system in which thin film is deposited on a substrate and the thin film on the substrate is etched in a vacuum chamber, a load-lock type multi-step vacuum system, in which the processing chambers are not exposed to atmosphere, has been widely used. FIG. 4 is a plan sectional view of a conventional multi-chamber type sputtering system provided with many processing chambers. This system consists of four processing chambers 1, two load-lock chambers 2, and the substrate transferring chamber 3. Substrate transferring chamber 3 has a substrate transferring device 4, whereby a substrate is transferred between a load-lock chamber 2 and a processing chamber 1, or between the processing chambers 1.
In general, with respect to the operation of exchanging a processed substrate with an unprocessed one, the working procedures are as follows. The gate valve 1a of one of the processing chambers 1 and the gate valve 2a of one of the load-lock chambers 2 are opened. A processed substrate is taken out of the processing chamber 1 by substrate transferring device 4, and returned to the load-lock chamber 2. A new unprocessed substrate is then taken out of the load-lock chamber 2 and put into the processing chamber 1. If the operation is performed according to these procedures, the processing chamber 1 will communicate with the load-lock chamber 2 through the substrate transferring chamber 3, thus increasing the risk that dust particles contaminate the space within the processing chamber 1.
To attempt to resolve this problem, it is possible to perform the operation so that these two gate valves, 1a and 2a, are not opened simultaneously. In other words, only the gate valve 1a of the processing chamber 1 is opened to take out the substrate, and the gate valve 1a of the processing chamber 1 is closed before the gate valve 2a of the load-lock chamber 2 is opened to return the processed substrate into the load-lock chamber 2. Thereafter, a new unprocessed substrate is taken out of the load-lock chamber 2, and then the gate valve 2a of the laod-lock chamber 2 is closed. Then, the gate valve 1a of the processing chamber 1 is opened again to transfer a new unprocessed substrate into the processing chamber 1. By using this working procedure, these two gate valves, 1a and 2a, cannot be opened at the same time.
However, this working procedure increases the time required to exchange the substrates, thus high production throughputs can not be maintained. Thus, to exchange the substrates in a short time without opening the two gate valves, it is known to provide two transferring robots in the substrate transferring chamber. FIG. 4 shows this type of substrate transferring device 4 provided with two transferring robots 4a and 4b.
A working procedure for exchanging the substrates with the substrate transferring device 4 of FIG. 4 is as follows. While a substrate is being processed in one of the processing chambers 1, the first transferring robot 4a takes a new substrate 5a out of the load-lock chambers 2, and stands by in the substrate transferring chamber 3. Then, after the processing of the substrate is completed and the gate valve 1a of the processing chamber 1 is opened, a second transferring robot 4b takes the processed substrate 5b out of the processing chamber 1. Immediately after that, the transferring robot 4a transfers a new substrate 5a into the processing chamber 1 to close the gate valve 1a. Then, while the substrate is being processed in the processing chamber 1, the second transferring robot 4b returns the processed substrate 5b into one of the load-lock chambers 2, and at the same time, the first transferring robot 4a takes a new substrate out of the load-lock chamber 2. This working procedure enables an enhancement in the productivity without opening the two gate valves, 1a and 2a, simultaneously.
The conventional substrate transferring mechanism, as shown in FIG. 4, is designed so that the productivity is not decreased without opening the two gate valves simultaneously by the use of two transferring robots. However, a disadvantage results because this structure requires movable parts which generate much more dust particles. Also, it is necessary to enlarge the space within the substrate transferring chamber to contain the two transferring robots in it. As a result, the capability to evacuate the processing chamber must be increased, and the area occupied by the whole system will also be larger.